The present invention relates to water-repellent composite grains, a method for producing the composite grains, and a water-repellent article using the composite grains.
Fluorine-containing resins are superior, for example, in water repellency and stain resistance and practically used in many fields. Polytetrafluoroethylene (PTFE) is one of the most water-repellent fluorine-containing resins.
A fluorine-containing resin which is higher in water repellency, such as PTFE, is worse in adhesion to another material (substrate). Therefore, it becomes difficult to coat a substrate with this resin. Even if a substrate is coated with this resin, the coated surface (water-repellent layer) becomes inferior in abrasion resistance and the like. Hitherto, for the purpose of improving the adhesion strength of a fluorine-containing resin, for example, a major surface of a sheet of PTFE or the like has been treated with metal sodium to activate the major surface, or a major surface of a PTFE sheet has been made rough through glow discharge or the like to anchor the PTFE sheet to a substrate. However, these treatments are complicated, and it is difficult to apply these treatments to a PTFE sheet having a complicated shape.